一次入海温带气旋边界层气象要素观测分析  

Observation and analysis of boundary layer meteorological elements of an extratropical cyclone blowing into the sea

作　　者：涂小萍 姚日升 杨豪 张程明 

机构地区：[1]宁波市气象局,浙江宁波315012

出　　处：《自然灾害学报》2013年第5期160-170,共11页Journal of Natural Disasters

基　　金：宁波市科技计划项目(2012C50044);国家重大科技支撑计划项目子课题(2011BAK07B02-05);浙江省气象局科技计划项目(2010YB05);宁波市气象局科技计划项目(NBQX2012009B)

摘　　要：基于宁波市凉帽山岛370 m高塔二维超声风速仪对2012年5月30-31日一次入海温带气旋边界层资料的分析发现：该气旋是造成浙江北部大范围暴雨的主要原因,所带来的灾害性大风分为2轮：第1轮是温带气旋入海发展引起的,各层次风速的增减基本同步,7级以上大风持续近5 h;第2轮大风系由弱冷空气与温带气旋形成的气压梯度导致,7级大风首先出现在199~232 m的塔层中上层,低层持续约1 h。两轮灾害性大风均伴有明显降水,且温带气旋导致的降水和大风明显比冷空气强。本次温带气旋边界层风速随高度的变化基本遵从指数律,但不同时段风廓线指数不同,大风前、大风时和大风后分别为0.093,0.067和0.041。水平风速脉动标准差和湍流强度在塔层不同高度表现不同,199 m和232 m处表现为水平风速标准差分布零散,湍流强度呈乘幂指数减小,其他层次风速标准差随风速大小呈线性变化,而湍流强度随风速变化不明显。大风时塔层阵风系数小于1.4,阵风强度小于0.6。连续功率谱分析表明：灾害性大风发生时,塔层瞬时风速周期不明显。Based on the observation data over May 30-31, 2012 on the 370 meters tower constructed on Liangmaoshan Island of Ningbo City, analysis is done on an extro-tropical cyclone affecting the Zhejiang coastal areas. Results show that the extra-tropical cyclone is the main reason causing the disastrous heavy rainfalls across the north Zhejiang Province. Disastrous strong winds occur twice in turn. The first duration was caused by the extra-tropical cyclone blowing into the sea, with velocities keeping at the same pace at all tower levels and lasting for about 5 hours. Pressure gradient due to the cyclone system and weak cold air mass is blamed for the second strong wind duration, with wind force 7 originating in 199-232m, then stretching up and down, and lasting for only 1 hour at low levels. Both strong wind durations are accompanied with torrential rainfalls, but rainfalls are much more significant for the low pressure winds. Wind speed follows exponential law with different indices during different periods, about 0.093, 0.067 and 0.041, respectively for before, during and after the strong wind periods. Wind standard deviations and turbulence intensities display differently at different levels. The standard deviation scattered vastly but turbulence intensity following a power law at 199m and 232m; while at the other levels, speed deviations follow a linear law, but no apparent tendency between turbulence intensities and speeds. Gust coefficients are less than 1.4 and intensities are less than 0.6 during strong wind durations. Successive power spectrum of instant speed shows no periodicity during strong wind.

关 键 词：浙江 温带气旋 冷空气 边界层 气象要素 

分 类 号：P458.2[天文地球—大气科学及气象学]